Study links endocrine-disrupting chemical exposure to poorer sleep and vitamin D deficiency

By Dr. Chinta SidharthanReviewed by Benedette Cuffari, M.Sc.Apr 30 2024

In a recent study published in the journal Nutrients, researchers investigate whether exposure to endocrine-disrupting chemicals (EDC) in the environment contributes to vitamin D deficiency and has a negative impact on sleep duration.

Study: Vitamin D Deficiency Exacerbates Poor Sleep Outcomes with Endocrine-Disrupting Chemicals Exposure: A Large American Population Study. Image Credit: Savanevich Viktar / Shutterstock.com

The health effects of EDC exposure

EDCs encompass a wide range of substances, such as pesticides, phenols, industrial chemicals, and plasticizers that can disrupt hormonal regulation, production, and metabolic processes. These chemicals significantly alter circadian rhythms and impact the quality and duration of sleep. As they are commonly found in various products used in daily life, these chemicals present a significant threat of exposure.

Bisphenol A (BPA) and phthalates, which are common EDCs used for human activities, have been shown to affect sex hormone levels and influence the hypothalamic-pituitary-adrenergic axis, thus leading to a wide range of sleep disorders. Alterations in sleep quality and duration can increase the risk of metabolic disorders such as diabetes, obesity, cardiovascular disease, immunological and neurological problems, as well as mental health disorders such as anxiety.

Vitamin D has a vital role in musculoskeletal health; however, emerging evidence indicates that this vitamin is also important for health outcomes associated with sleep. Therefore, understanding whether EDC exposure can disrupt vitamin D metabolism is imperative to improving overall sleep outcomes.

About the study

In the present study, researchers evaluate whether exposure to EDCs was associated with disruptions in sleep duration in adults using six statistical models. These models included the elastic net, the quantile G-computation, weighted quantile sum regression, Bayesian kernel machine regression, and generalized linear models.

Study participants were recruited among individuals registered in the United States National Health and Nutrition Examination Study, which evaluates the nutrition and health of the overall population through surveys.

Data used for the analysis included urine test results for phthalates and BPA, as well as information on smoking behavior, alcohol intake, thyroid-related health concerns, race, education levels, body mass index (BMI), household income, marital status, physical activity levels, age, and occurrence of any endocrine diseases.

Phthalates and BPA were common EDCs considered in the study. Nevertheless, urine samples were also further analyzed through high-performance liquid chromatography (HPLC) and electrospray ionization tandem mass spectrometry to detect other environmental EDCs.

The Munich Chronotype Questionnaire was used to obtain data on sleep duration. Additionally, blood samples from all the participants were used to determine the serum vitamin D levels through liquid chromatography and mass-spectrometry methods.

Study participants with vitamin D levels below 30 nmol/liter or 12 ng/mL were categorized as deficient in vitamin D. The analysis considered age, gender, ethnicity, education levels, household income, smoking status, BMI, and alcohol consumption considered as covariates. Spearman’s correlation coefficient was used to evaluate the correlation between various EDCs found in the urine samples.

Study findings

Individuals with vitamin D deficiency had shorter sleep durations than individuals with normal vitamin D levels. Furthermore, exposure to EDCs such as triclosan, mono-ethyl phthalate, and mono-benzyl phthalate in isolation or together was associated with both shorter sleep duration and vitamin D deficiency.

Individuals who were deficient in vitamin D experienced shorter sleep durations after exposure to triclosan as compared to those with normal vitamin D levels. Exposure to benzophenone-3 and mono-(3-carboxypropyl) phthalate was also associated with low vitamin D levels.

A mixed exposure evaluation found that both triclosan and mono-benzyl phthalate exposure significantly impact sleep durations, with vitamin D-deficient individuals experiencing longer sleep durations. This finding was similar to previous reports in which exposure to high levels of EDCs was associated with delays in falling asleep and longer sleep durations.

Conclusions

Exposure to EDCs, both alone and in combination, significantly impacts sleep duration. EDC exposure might also contribute to vitamin D deficiency, further exacerbating adverse sleep outcomes.

These findings indicate that vitamin D supplementation could help mitigate the negative impacts of EDC exposure on sleep duration. Sleep deprivation is associated with a greater risk of mental health disorders like depression; therefore, the study findings also offer novel approaches that can be used to both prevent and treat the effects of EDC exposure that may exacerbate existing psychiatric illnesses.